Changing priorities of modules

There is a short and long version #Short version

• List modules: Run utils/lodspk.sh list modules
• Position the desired module (e.g., type) in a specific position: Run utils/lodspk.sh enable module type 1
• List modules again to confirm that changes occurred: Run utils/lodspk.sh list modules

#Long version LODSPeaKr runs one module per URI request (see Modules for more info). By default, the modules available are executed in the following order:

1. Static
2. Service
3. Type

Why change it?

An example of when you may want to change it: Imagine you have URIs following the following convention

http://example.org/id/thing_1
http://example.org/id/thing_2
http://example.org/id/thing_2/subthing_1
http://example.org/id/thing_2/subthing_2
http://example.org/id/thing_3

Now, you want to mint http://example.org/id to be the document that returns a list of resources based on a certain SPARQL query. The way of doing this is to create a service called id by running

utils/lodspk.sh create service id

Now you can start working on your query to retrieve the right resources. But wait! now URIs like http://example.org/id/thing_1 won't get served, since LODSPeaKr will interpret that you are requesting http://example.org/id using thing_1 as a parameter. This happens because by default the service module has priority over type module.

Changing priorities

First, go to the LODSPeaKr directory and run

utils/lodspk.sh list modules

You should see something like

0) static
1) service
2) type

this indicates that when receiving a request, LODSPeaKr will first ask to the static module if it should deal with such request. If not, it will ask the service module the same. In our case, the service module will recognize the pattern id/* in the URI and given that it exist a component called id it will accept the request. Since service module will take care of the request, LODSPeaKr will never ask to the type module, which is the one that should actually serve that URI.

In order to change the priorities you can run

$ utils/lodspk.sh enable module type 1
Module type enabled successfully

This tells LODSPeaKr that module type should be positioned in place 1. Every other module will be displaced one position. Listing the modules again should reflect the changes

utils/lodspk.sh list modules
0) static
1) type
2) service

Now when http://example.org/id/thing_1 is requested, LODSPeaKr will ask the static module and then to the type module. Since this URI exist in the triple store, type module will be served it based on whatever component is available.